Save Oliver Perez!

As the Mets assess ways to improve their pitching staff this offseason, Oliver Perez, who has been a mainstay of the starting rotation, is mentioned as one of several options. But if the Mets are serious about consolidating 2008’s gains, they have no choice but to sign Perez, who is the best of their plausible alternatives, both in 2009 and beyond.

The Mets, despite a laughably poor bullpen, remained in playoff contention until the season’s final day for two reasons: the offense and the starting pitching. And the three starters that kept the Mets in the race were Johan Santana, Mike Pelfrey and Oliver Perez.

Still, the most frequent attack on Perez is that he is somehow too inconsistent to be relied upon. But leaving aside the fact that he just completed his age-26 season, and is likely to be getting even better, the charge simply isn’t true.

From June 3 through the end of the season, Perez pitched at least six innings in 17 of 22 starts, striking out roughly a batter an inning and pitching to a 3.56 ERA. While he struggled mightily in the season’s first two months, his effort from June 3 on matches almost exactly his 2007 season, when he struck out nearly a batter an inning and pitched to a 3.56 ERA as well. His April-May 2008 is what looks like the outlier as Perez enters his age-27 season—no surprise for a developing pitcher.

So what is reasonable to expect from Perez, should the Mets sign him to the four or five year deal likely required? A quick check of baseball-reference.com for the most similar pitchers through age 26 provides a helpful guide.

Tops on the list is Mark Langston, a pitcher who, like Perez, had control problems early in his career. But Langston, beginning at age 27, posted league average or better ERAs in eight of his next nine seasons, before starting to break down at age 35. Ultimately, his strikeout rate overcame his walk issues. Should the Mets receive Langston’s peak with a Perez contract, they’d be quite satisfied.

Close behind on the list is Bobby Witt, who also pitched until age 37, though an injury history that Perez doesn’t have makes that comparison less germane. Third on the list is Frank Viola, who pitched the Twins to a World Series championship in his age-27 season, won 24 games and the Cy Young at age 28, and pitched effectively through age-33, though his strikeout rates began to plummet by age 31.

Of course, even if the Mets sign Perez to a five-year deal, that would only take him through his age-31 season. That is the largest advantage Perez holds over the other free-agent options New York has, especially Derek Lowe, who seems to be high on the team’s wish list. Lowe supposedly is the safer choice, based on track record and consistency.

But Lowe pitched 211 innings in 2008, Perez 194. Lowe had a similar arc in his year to Perez, in fact, pitching to a 2.49 ERA over his final 24 starts, but a 5.34 ERA in his first ten. And while Perez is supposedly much more inconsistent, Lowe reached six innings in 18 of his final 24 starts—no noticeable difference from Perez’s 17 of his final 22.

So while Lowe had a better overall 2008, Perez had a better 2007. Should the Mets sign Lowe to a three-year deal, they’d be getting his age-36, age-37 and age-38 seasons. But with a strikeout rate of just above six per nine innings, his long-term prospects are considerably lower. His most similar pitcher, Don Robinson, retired at age 35. Second-most similar was Danny Darwin, who pitched effectively until age 40. But most of the comparables on the list were near the end of their time as front-line starting pitchers by age 36.

So if not Lowe, then who? Compared to the finest pitcher on the free agent market, C.C. Sabathia, Perez’s accomplishments fail to impress. But Sabathia will cost roughly twice as much annually as Perez, and likely will receive a six- or seven-year commitment, while Perez will likely get five years at most. Sabathia has a lot more mileage on his arm than Perez does, making him more of a risk. And the Mets likely need some of the cash it would take to sign him to solidify the bullpen.

And compared to the rest of the free agents, Perez lacks the injury history (A.J. Burnett, Ben Sheets, Brad Penny, Jason Jennings) that should give any team pause before handing out a long-term deal, while pitching at a much higher level than anyone else on the free agent list.

It is a mistake to assume that Perez will make the leap from frontline starter to Cy Young contender. But he the best bet to remain a solid rotation member of any free agent besides the exorbitantly expensive Sabathia, and the chances he becomes an ace are far from trivial. The Mets need to take advantage of their exclusive negotiating window and sign Perez now.